Method and means for detecting dyslexia

Abstract

The specification discloses a diagnostic device and method for detecting various neurological conditions, particularly dyslexia. Eye movement patterns of the subject to be tested are separated into saccadic movement (both progressive and regressive) vergence, pursuit movements and fixations, and the subject's specific eye movement pattern, as evaulated against a specific stimulus, and normal patterns is used for diagnostic purposes. A variety of eye movement detectors is disclosed, together with a sampling means which evaluates the eye position at intervals of less than 10 milliseconds. A data processing means is used to isolate the significant samples and categorizes the retained data samples into the foregoing eye movements. The eye movement patterns are then evaluated against a statistical data base to determine the kind and severity of the diagnosed condition. For example, dyslexic individuals exhibit a high number of regressive saccades, while drug and alcohol impaired individuals are unable follow a stimulus with a pursuit movement, but must relay on a series of short saccades.

I claim: 
     
       1. An automated system for determining the existence of temporary neurological impairment from alcohol, said system comprising: (a) means for stimulating a predetermined pattern of eye movement in a subject to be evaluated for said impairment, said pattern including a slowly moving stimulus for a portion thereof to stimulate pursuit eye movement in the subject,   (b) means for detecting eye movement in a subject observing said means for stimulating eye movement, said detecting means providing an electrical output signal in response to said movement,   (c) processor means for receiving said electrical output signal, said processor means further including, (i) means for sampling the output signal to obtain a series of successive eye positions,   (ii) means for converting said successive eye positions to data representing eye movements,   (iii) means for analyzing said data by direction, duration, and amplitude to categorize said eye movements and to differentiate between saccadic movements, pursuit movements and fixations,   (iv) means for comparing the number and placement of saccadic eye movements with respect to stimulated pursuit movements to diagnose the existence of the neurological impairment,     (d) output means for enabling display of said diagnosis.   
     
     
       2. An automated system for determining the existence of said neurological impairment as claimed in claim 1, said system further comprising a comparator means for comparing the pattern of said categorized eye movement with predefined patterns to determined the existence of said neurological impairment in the subject. 
     
     
       3. An automated system for determining the existence of said neurological impairment as claimed in claim 1, said system further comprising a calibration means for linearizing the output signals from said eye movement detector means, before said signals are categorized into eye movements. 
     
     
       4. An automated system for determining the existence of said neurological impairment as claimed in claim 3 wherein the existence of said impairment is determined by comparing the percentage of saccade movements with a predefined statistical average. 
     
     
       5. An automated system for determining the existence of said neurological impairment as claimed in claims 2 or 3 or 4 wherein said means for stimulating eye movements includes a synchronization means for correlating detected eye movements with a predetermined stimuli. 
     
     
       6. An automated system for determining the existence of said neurological impairment as claimed in claim 5 wherein said predetermined stimuli appear on an electronic display device. 
     
     
       7. An automated system for determining the existence of said neurological impairment as claimed in claim 2 or 3 or 4 wherein said means for converting said successive eye positions into data convert said positions into x-y coordinate values. 
     
     
       8. An automated system for determining the existence of said neurological impairment as claimed in claim 1 or 2 or 3 wherein said means for analyzing said data differentiates between saccadic progressions and pursuit movements. 
     
     
       9. An automated system for determining the existence of said neurological impairment as claimed in claim 1 or 2 or 3 wherein said means for analyzing said data compares the length of a fixation period with the length of a fixation stimulus. 
     
     
       10. An automated system for determining the existence of said neurological impairment as claimed in claim 1 or 2 or 3 wherein said means for analyzing said data compares the average and total length of forward and regressive eye movements with the average and total length of all eye movements. 
     
     
       11. An automated system for determining the existence of said neurological impairment as claimed in claim 1 or 2 or 3 wherein said output means displays eye movement categories as a series of x-y movements in relation to time. 
     
     
       12. A method for determining the existence of temporary neurological impairment resulting from alcohol, said method comprising: (a) stimulating a pursuit eye movement in a subject to be tested for said impairment,   (b) detecting eye movement in a subject to be tested for said impairment,   (b) detecting eye movement in said subject being stimulated, and converting the magnitude and direction of eye movement to an electronic signal,   (c) sampling the electronic signal and converting said samples to data representing eye positions,   (d) automatically analyzing said data samples with an electronic data processor and according to a predetermined program by direction, duration, and amplitude movements, pursuit movements and fixations.   (e) comparing the number and placement of saccadic movements with the stimulated pursuit movements to determine the existence of said neurological impairments.   
     
     
       13. A method for identifying the existence of said neurological impairment as claimed in claim 12 which further includes the step of comparing a pattern of analyzed eye movements with a predefined pattern to determine the existence of said impairment. 
     
     
       14. A method for identifying the existence of said neurological impairment as claimed in claim 13 which further comprises the step of linearizing the output signals from aid eye movement detector before said signals from said eye movement detector are analyzed. 
     
     
       15. A method for identifying the existence of said neurological impairment as claimed in claim 13 or 14 which further comprises the step of synchronizing the detected eye movements with a predetermined stimulus. 
     
     
       16. A method for identifying the existence of said neurological impairment as claimed in claim 13 or 14 wherein the step of stimulating eye movement is performed with one or more stimuli created on the face of an electronic display device. 
     
     
       17. An automated system for determining the existence of temporary neurological impairment from alcohol, comprising: (a) means for stimulating a predetermined pattern of eye movement in a subject to be evaluated for said impairment said pattern including a slowly moving stimulus for a portion thereof to stimulate pursuit eye movement in the subject,   (b) means for detecting eye movement in the subject, observing said means for stimulating eye movement, said detecting means providing an electrical output signal in response to said movement,   (c) processor means for receiving said electrical output signal, said processor means further including: (i) means for sampling the output signal to obtain a series of successive eye positions,   (ii) means for linearizing and converting said successive eye positions into data representing eye movements, said linearization being conducted on the successive eye positions,   (iii) means for analyzing said eye movements and differentiating between forward and reverse saccadic movements, pursuit movements and fixations,   (iv) means for comparing said eye movements to predetermined patterns to determine the existence of said impairment,     (d) output means for enabling display of said diagnosis.